docs: def _setup_ipc(self):
          '''
          Subscribe to the pub IPC
          and publish the messages
          on the right transport.
          '''
          self.ctx = zmq.Context()
          log.debug('Setting up the %s publisher subscriber #%d', self._transport_type, self.pub_id)
          self.sub = self.ctx.socket(zmq.SUB)
          self.sub.connect(PUB_IPC_URL)
          self.sub.setsockopt(zmq.SUBSCRIBE, b'')
          try:
              self.sub.setsockopt(zmq.HWM, self.opts['hwm'])
              # zmq 2
          except AttributeError:
              # zmq 3
              self.sub.setsockopt(zmq.RCVHWM, self.opts['hwm'])